import numpy as np

matrix = np.random.randint(0, 100, size = (3, 4))
print("随机矩阵:\n", matrix)

rowSum = np.sum(matrix, axis = 1)
print("每行的和: ", rowSum);

columnMeans = np.mean(matrix, axis=0)
print("每列的平均值：", columnMeans)

columnMaxIndexes = np.argmax(matrix, axis = 0)
print("每列最大值索引: ", columnMaxIndexes) 